The Effect Of Porous Layer On The Performance And Stability Of Oxygen Electrode In Solid Oxide Cells

Solid oxide cells?SOC?is an electrochemical energy conversion device with high energy conversion rate and environmentally friendly,which can be operated in solid oxide fuel cell?SOFC?and solid oxide electrolytic cell?SOEC?modes,so it has broad application prospects.At present,one of important factors limiting the large-scale commercialization of SOC is the long-term stability of the oxygen electrode.In this paper,in the purpose of improving stability of(La_0.75Sr_0.25)_0.95MnO_3-??LSM?oxygen electrode,the effect of porous YSZ layer on the performance and stability of LSM oxygen electrode in two modes of SOC?cathode polarization,anodic polariztion?was systematically studied.In addition,the DRT program of the impedance spectrum was independently written by Matlab.A porous YSZ layer was prepared on the surface of the dense YSZ electrolyte by spin coating,and the half-cell was prepared with LSM electrode.The performance and stability of the LSM electrode were studied by three-electrode method.Firstly,the performance and stability of LSM electrode in anodic polarization was studied.The results show that the introduction of the porous layer increases the stability of the LSM electrode during anodic polarization.A three-suqency chronopotentiometry method was used for potential relaxation observation of LSM electrode to evaluate the oxygen pressure of the LSM electrode/electrolyte interface region.reduces the oxygen pressure at the LSM electrode/electrolyte interface.The results show that the introduction of porous YSZ layer accelerates the diffusion of oxygen at the electrode/electrolyte interface into air lead to the significant reduction of oxygen pressure at the LSM electrode/electrolyte interface.The DRT program was written by Matlab.Performing DRT processing on the impendance spectrum of LSM electrode in porous layer and non-porous layer samples were carried out.The results shown that the introducation of the porous layer increases the capacitance values of the corresponding charge transfer process of the LSM electrode.The capacitance value is proportional to the length of the three phase boundary?TPB?,the introduction of the porous layer extends the three-phase interface region.The effect of the porous layer on the performance of oxygen reduction reaction of LSM electrode was further studied.The cathodic polarization of LSM electrode at 200mA cm^-2 was carried out.It is found that the introduction of the porous layer improves the performance of oxygen reduction of LSM electrode.Subsequnently,the performance of LSM electrode during anodic-cathodic repeated polarization was studied.The results show that the introduction of porous layer improves the staility of LSM electrode during anodic-cathodic repeated polarization,providing the basis of the application of the porous in SOC.Finally,in the Cr-containing atmosphere,the introduction of the porous layer significantly inhibits the degradation of the performance of the LSM electrode.The introduction of the porous layer increases the reactive site and reduces the relative current density at the active site,thereby reducing the gaseous Cr species deposition at the reactive site.